U.S. patent number 5,057,083 [Application Number 07/385,010] was granted by the patent office on 1991-10-15 for vascular dilator with truncated tip.
This patent grant is currently assigned to C. R. Bard, Inc.. Invention is credited to Barry N. Gellman.
United States Patent |
5,057,083 |
Gellman |
October 15, 1991 |
Vascular dilator with truncated tip
Abstract
A vascular dilator has a truncated tip adapted to reduce the
risk of trauma to a blood vessel into which the dilator is to be
inserted. The vascular dilator comprises an elongate tube having a
guide member lumen of uniform diameter in which a guide member may
pass. The thickness of the walls of the elongate tube decreases at
the distal portion to create a tapered configuration. The distal
portion terminates in an outlet defined by first and second arcuate
segments. The first arcaute segment lies generally in a plane
perpendicular to the longitudinal axis of the tube, whereas the
second segment lies so as to meet the first segment at angle in the
range of 30.degree. to 60.degree..
Inventors: |
Gellman; Barry N. (Nashua,
NH) |
Assignee: |
C. R. Bard, Inc. (Murray Hill,
NJ)
|
Family
ID: |
23519667 |
Appl.
No.: |
07/385,010 |
Filed: |
July 25, 1989 |
Current U.S.
Class: |
604/164.1;
604/523; 604/272 |
Current CPC
Class: |
A61M
25/0662 (20130101); A61M 25/0068 (20130101) |
Current International
Class: |
A61M
25/06 (20060101); A61M 25/00 (20060101); A61M
005/178 () |
Field of
Search: |
;604/164,272,264,280 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Bahr; Robert
Assistant Examiner: Doyle; J.
Attorney, Agent or Firm: Wolf, Greenfield & Sacks
Claims
Having thus described the invention, what I desire to claim and
secure by letters patent is:
1. A vascular dilator for use with a guide member comprising:
an elongate tube having a uniform inner diameter defining a guide
member lumen;
the dilator having a distal portion with a distally reducing wall
thickness to define a tapered configuration, the distal portion
terminating in an outlet with an edge having a first arcuate
segment portion that lies generally in a plane perpendicular to the
longitudinal axis of the tube and a second arcuate segment that
extends from one end of the first segment to the other end of the
first segment, said segments meeting at an angle that lies in the
range of between about 30.degree. to about 60.degree..
2. A vascular dilator as defined in claim 1 wherein a chord line
extending between the junctures of the segments intersects a
projection of the guide member lumen so that the area circumscribed
by the chord line and the first arcuate segment is no more than
one-half of the projected area of the lumen.
3. A vascular dilator as defined in claim 2 wherein the juncture of
the segments lie on points that intersect the diameter of a circle
that is partly defined by the first arcuate segment.
4. A dilator as defined in claim 2 wherein said area is less than
one-half of the lumen.
5. A vascular dilator as defined in claim 1 wherein said first
arcuate segment defines an arc no greater than about
180.degree..
6. A vascular dilator as defined in claim 1 wherein said second
arcuate segment defines an axially projected arc of at least about
180.degree..
7. A dilator as defined in any of claims 1-6 further comprising, in
combination, said guide member, said guide member extending through
the lumen of the dilator.
8. A dilator as defined in any of claims 1-6 further comprising, in
combination, said guide member and a catheter, the guide member
extending through the lumen of the dilator and the catheter being
mounted on the dilator.
9. A vaculator dilator as defined in claim 1 wherein the first
arcuate segment lies in a circle in the plane perpendicular to the
longitudinal axis of the tube, said circle being centered at the
longitudinal axis of the tube and having a radius extending from
the longitudinal axis of the tube to the first arcuate segment.
10. A method for dilating a blood vessel comprising:
percutaneously inserting a guide member into the blood vessel of a
patient; and
providing a dilator as defined in any one of claims 1-6; and
advancing the dilator over the guide member into the blood vessel
until the second arcuate segment reaches a wall of blood vessel so
that the first arcuate segment engages and displaces an outer
surface of the blood vessel so that further advancement of the
dilator does not bluntly engage the outer surface of vessel;
further advancing the dilator over the guide member into the blood
vessel so that the wall of the blood vessel rides over the second
arcuate segment without harming the blood vessel.
11. A method as defined in claim 10 further comprising rotating the
dilator while inserting it into the vessel.
Description
FIELD OF THE INVENTION
This invention relates to vascular dilators for dilating a needle
puncture in a blood vessel in preparation for insertion of a larger
diameter catheter into the blood vessel.
BACKGROUND OF THE INVENTION
Vascular dilators are commonly used when inserting a catheter into
a blood vessel in order to widen the hole formed by the initial
needle or scalpel puncture so that it is better able to receive the
larger diameter catheter. The use of the dilator gradually enlarges
the hole. In a typical procedure, a hollow needle is percutaneously
inserted into the blood vessel and an elongate, slender guide
member, such as a cannula or a guidewire is advanced through the
hollow needle into the blood vessel. The needle then is removed
over the guide member leaving the guide member in place in the
blood vessel and extending proximally out of and through the
patient's skin. The hole left by the needle in the blood vessel
typically is too small to permit the catheter to be passed
therethrough. A dilator is provided to widen the hole. Dilators
commonly are in the form of a flexible plastic tube having a guide
member lumen adapted to be passed over the guide member. The
dilator is of uniform wall thickness except for a distal portion
which tapers in a distal direction to the circular distal outlet
opening at the distal end of the dilator. The wall thickness of the
dilator at the distal tip is relatively thin to facilitate its
entry into the hole made by the needle. As the dilator is advanced
over the guide member through the puncture hole, the tapered distal
portion presents a progressively wider diameter to the puncture
hole, thus gradually enlarging the hole. The catheter may be
mounted on and carried by the dilator so that once the dilator has
been inserted to its full diameter into the blood vessel, the
catheter then may be advanced over the dilator and through the
enlarged puncture hole into the blood vessel. The dilator and guide
member then may be withdrawn leaving the percutaneously placed
catheter in place in the blood vessel.
Although there is a relatively close fit between the guide member
and the circular opening defined by the distal tip of the dilator
about the guide member, there necessarily is some clearance and it
sometimes occurs that the intima of the blood vessel may become
pinched or caught between the edge at the distal tip of the dilator
and guide member. The blood vessel thus may become damaged,
particularly if the pinching is unnoticed and the insertion of the
dilator is continued. Therefore, there is a need for a dilator that
reduces the risk of such traumatic injury to the blood vessel. It
is among the general objects of the invention to provide an
improved dilator that reduces the risk of pinching the blood vessel
and reduces trauma to the blood vessel.
SUMMARY OF THE INVENTION
The dilator of the present invention has a plastic tubular sheath
having a guide member lumen extending from its proximal to its
distal end. The guide member lumen is of uniform diameter fully
along its length. The distal end of the sheath has a tapered outer
diameter and tapers to a thin wall. The clearance between the guide
member and lumen of the sheath is relatively small, of the order of
less than 0.01". The distal end of the lumen is truncated to lie
generally along a plane that lies in an acute angle to the dilator
axis and which intersects the general plane of the otherwise
circular opening and the guide member lumen. The truncated portion
meets the tissue of the blood vessel in a manner that enables the
blood vessel tissue to slide onto the truncated portion without
being pinched. The truncated portion overlies a projected area of
the guide member lumen that is at least half of the projected
area.
It is among the objects of the invention to provide an improved
blood vessel dilator adapted to be passed over a guide member. A
further object of the invention is to provide an improved blood
vessel dilator that reduces the tendency for the blood vessel to
become pinched between the guide member and the distal tip of the
vessel dilator.
A further object of the invention is to provide a vessel dilator
having a tip construction which facilitates smooth entry of the
dilator into the blood vessel.
DESCRIPTION OF THE DRAWINGS
The foregoing and other objects and advantages of the invention
will be appreciated more fully from the following further
description thereof, with reference to the accompanying drawings
wherein:
FIG. 1 is an illustration of a guide member, dilator and catheter
percutaneously placed within a blood vessel;
FIG. 2 is an enlarged cross-sectional illustration of a typical
dilator of the prior art which is in common use;
FIG. 3 is an illustration of the prior art dilator of FIG. 2
showing the manner in which it may tend to pinch the blood
vessel;
FIG. 4 is a side elevation of the tip construction of the dilator
in accordance with the invention;
FIG. 5 is an illustration of the tip construction of the invention
as seen from the line 5--5 of FIG. 4 (top view);
FIG. 6 is an end view of the dilator as seen from the left of FIG.
4; and
FIG. 7 is an illustration of the dilator of the invention being
inserted into a blood vessel.
DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENT
FIG. 1 illustrates the manner in which a catheter 10 is inserted
percutaneously into the blood vessel 12 of a patient using a guide
member 14 and a dilator 16. In the illustrations and following
description, the guide member 14 is illustrated as being a
guidewire, although it should be understood that any elongate
flexible guiding member may be employed such as a cannula or wire
element or other suitable synthetic material which may be coated
with or formed from a lubricious material. The procedure typically
involves an initial needle puncture with a hollow needle (not
shown) that is inserted through the patient's skin into the blood
vessel. The distal end of the guide member 14 then is passed
through the hollow needle into the patient s blood vessel. The
needle then is withdrawn over the proximal end of the guide member
14. The catheter 10 typically will be carried on the dilator 16
which passes through the lumen of the catheter 10 and projects
distally beyond the distal end 18 of the catheter 10. The distal
portion 20 of the dilator 16 is tapered so that the wall thickness
of the dilator at its distal tip 22 is thinner than in the more
proximal portions of the dilator and will present a relatively
smooth transition from the guide member to the dilator as the
dilator advances through the wall of the blood vessel. The dilator
is advanced to progressively widen the opening in the blood vessel
Once the full diameter of the dilator has been inserted into the
blood vessel, the catheter then may be advanced into the blood
vessel, the dilation having widened the hole to facilitate entry of
the larger diameter catheter. Once the catheter 10 has been
inserted into the blood vessel 12, the guide member 14 and dilator
16 are removed, leaving the catheter in place in the blood vessel
to perform its intended function.
The dilator typically is formed from a lubricious plastic material
such as polytetrafluoroethylene or polyethylene to provide a high
degree of lubricity in the blood vessel as well as with respect to
movement of the catheter over the dilator 16. The dilator typically
is provided with a hub at its proximal end and is of a length
slightly greater than the length of the catheter assembly so that
when the hub of the dilator is advanced fully distally against the
proximal end of the catheter assembly, the distal portion 20 of the
dilator will project beyond the distal end of the catheter. Thus,
the length of the dilator will depend on the length of the
catheter.
FIG. 2 illustrates in enlarged detail the distal tip of a
conventional dilator in relation to a guide member 14. Although the
wall of the dilator is progressively thinner in a distal direction,
it nevertheless terminates in a blunt annular face 24. Typically,
the annular face 24 may define a terminal wall thickness of the
order of up to 0.01". Additionally, there is a slight clearance
between the lumen 26 of the dilator 16 and the guide member 14.
Typically, the slight clearance at the distal tip of the dilator 16
is defined by an annular cylindrical, untapered surface 25. As
shown in FIG. 3, when such a conventional dilator 16 is advanced
over the guide member 14 into the blood vessel 12, it may catch and
pinch the wall or a portion of the wall of the blood vessel, such
as the delicate intimal lining, in the annular clearance between
the guide member 14 and dilator tip 22. Should the blood vessel
become caught, it may not be noticed and further advancement of the
dilator into the blood vessel may cause injury to the blood
vessel.
FIGS. 4-6 illustrate the improved dilator of the present invention.
In accordance with the invention, the distal tip of the dilator is
formed with a truncated segment that lies generally along a plane
that intersects the plane of the otherwise generally circular
opening. More particularly, the distal tip of the present invention
may be considered as having an edge defined by a first arcuate,
such as partially circular segment 28 that lies generally in a
plane perpendicular to the longitudinal axis of the dilator 16 and
a second arcuate segment 30 that extends from one end of the first
arcuate, such as partially circular segments 28, at a junction 32,
to the other end of the first arcuate, such as partially circular
segment 28 at a junction 34. Preferably, the second arcuate segment
lies generally in a plane that meets the plane of the first
arcuate, such as partially circular segment 28 at an angle A of
between approximately 30.degree. to 60.degree.. The second arcuate
segment preferably is planar although it could be provided with
somewhat of a curved configuration, it not being strictly essential
that the segment be perfectly planar. In the preferred embodiment,
the junctures 32, 34 define a chord (as seen from a projected end
view such as FIG. 6) with the area circumscribed by the chord and
the first arcuate, such as partially circular segment 28 being no
greater than one-half the axially projected area of the lumen.
Thus, the arcuate, such as partially circular segment 28 preferably
defines an arc not substantially greater than about 180.degree. and
may define an arc less than 180.degree.. Thus, the second arcuate
segment 30 defines an axially projected arc that is at least equal
to about 180.degree.. It should be understood that the juncture 32,
34 and the outermost edge of segment 28 may be rounded and need not
be geometrically sharp points. The inner surface, 35, at the distal
end of the guide member lumen of the dilator 16 preferably is
untapered to define a generally cylindrical configuration.
FIG. 7 illustrates the manner in which the dilator of the present
invention enters the puncture hole of an artery. The needle
typically is inserted at an acute angle to the artery and the guide
member extends at such an angle into the artery so that it will
guide the dilator into the artery at such angle. As illustrated in
FIG. 7, it can be seen that the first arcuate, such as partially
circular segment 28 initially contacts the outer surface of the
blood vessel 12 and pushes it down and out of the way so that it
advancement will not bluntly engage any portion of the blood
vessel. As the first arcuate, such as partially circular segment 28
begins the enlargement of the needle hole, the hole widens until
the junctures 32, 34 have reached the blood vessel wall. The blood
vessel wall then rides up onto the second arcuate segment 30 so
that continued advancement of the dilator causes the blood vessel
wall to ride smoothly over the second arcuate segment, thus
progressively enlarging the hole without risk of pinching the
intimal lining of the blood vessel During insertion, it may be
desirable to impart a slight rotational motion to the dilator
simultaneously as is advanced axially.
From the foregoing, it will be appreciated that the present
invention provides an improved dilator construction and method for
dilating a blood vessel during wire or similarly guided insertion
of a catheter. It should be understood, however, that the foregoing
description of the invention is intended merely to be illustrative
thereof and that other embodiments and modifications may be
apparent to those skilled in the art without departing from its
spirit.
* * * * *